In an adaptive bit rate streaming system, a content item is encoded into multiple streams of different bit rates, with each stream being divided into sequential segments of a given duration (e.g. 2-10 seconds). A manifest file is transmitted to user devices, e.g. by an adaptive bit rate server, that lists the segments of the content item, the different bit rates at which each segment has been encoded, and a network identifier for accessing each segment, e.g. a uniform resource locator (URL). A user device may retrieve each segment at the bit rate that is appropriate for the user device, e.g. based on network bandwidth conditions and device capabilities that are determinable by the user device. In this manner, the user device may adaptively retrieve segments that are encoded at different bit rates in accordance with changing network bandwidth conditions. However, although many user devices may be capable of adaptive bit rate streaming, there may be legacy content delivery networks that do not have adaptive bit rate streaming capabilities.